1. Field of the Invention
The present invention relates to a toothed coupling for tracked vehicles.
2. Description of the Related Art
British reference GB-2 241 766 discloses a toothed coupling which connects an output drive shaft of a transmission to a track drive wheel. Such couplings enable the final drive to be decoupled from the main transmission to allow the vehicle to be towed over relatively long distances, for example, without causing damage to the transmission or removing the transmission from the vehicle.
The coupling disclosed comprises a gear arranged on the output drive shaft of the transmission. An internally toothed coupling sleeve is slipped onto the gear. The other internally toothed end of the coupling sleeve is in engagement with another gear arranged on the input shaft of the final drive. This drive connection can be released by axial displacement of the coupling sleeve towards the main transmission.
The coupling sleeve has a radially inward extending flange having radial holes arranged between the toothed ends of the sleeve. This flange is guided in an axially displaceable manner on a hub that has radial notches and is secured on the output shaft. The flange be fixed in the coupled or decoupled position. The hub is secured on the output drive shaft in a manner that allows angular movement. Balls are pressed into the notches of the hub from the flange side by spring force. The balls are inserted into radial holes in the flange. Hole springs and additional pins are arranged in the holes for securing the balls. The pins are supported by a collar that surrounds the coupling sleeve.
For axial displacement of the coupling sleeve, the collar has a radially projecting lever screwed onto it for turning the collar a predetermined angle in the circumferential direction. This brings the collar into a position opposite hole recesses which give the pins displacement space in the radial direction. The balls are thus released and can slide out of the respective notch in the hub against the spring force. The coupling sleeve can then be displaced into the coupled or decoupled position in the axial direction by means of the lever. In the respective end position, the collar must be turned back into the securing position, where it engages by means of spring force. Finally, the lever must be removed.
The fact that displacement is effected by the radially outward-projecting lever means that force is introduced into the coupling sleeve in an unfavourable manner. Thus, a large force is required and must be increased even further due to incipient tilting of the sleeve. The fact that the lever is arranged between the main transmission and the vehicle wall makes it necessary to provide a clearance at this point to allow access to the coupling sleeve.
It is the object of the present invention to provide a toothed coupling which reliably allows complete coupling and decoupling in a simpler manner.
Pursuant to this object, and others which will become apparent hereafter, one aspect of the present invention resides in a toothed coupling for tracked vehicles having a main transmission and a final drive. The toothed coupling includes a first externally toothed gear connectable to the main transmission, a second externally toothed gear connectable to the final drive, and a coupling sleeve having an internal toothing in engagement with the first externally toothed gear and being engagable with the second externally toothed gear. The coupling sleeve is axially displaceable and fixable at defined positions. The coupling sleeve has a flange that extends radially inward substantially perpendicular with respect to an axis of the coupling sleeve. A spindle is connected to the flange part and arranged coaxially with the coupling so as to be capable of rotating the coupling sleeve about the axis. A spindle nut is arranged on the spindle and a blocking part is arranged on an end of the spindle is radially displaceable. A tool is provided for engaging the blocking part, the tool being removable from the blocking part only at defined axial positions of the spindle. Since the displacement force is introduced centrally in the present invention, tilting of the coupling sleeve is avoided, and small forces are required for coupling or decoupling.
A complete coupling and decoupling operation is made possible even without visual monitoring because of the advantageous configuration of the toothed coupling of the present invention. Due to the advantageous central operation of the toothed coupling, no clearance is necessary between the main transmission and the vehicle pan, making it possible to construct a narrower vehicle or to use wider transmissions.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.